System of motor control.



W. H. POWELL. 'SYSTEM OF MOTOR CONTROL APPLICATION FILED JAN. 28, 1907.

Mm e3 PATENTED SEPT. 10, 1907 To all u'izon Bo it kn of the UnitedStates, rc id oi Hamilton and State of Uhio, ho

pecially to control.

, LUIll-XLMERS COMPANY, A .JRIG MUNUFAGTURI lG'COM- been ozonoscd in nitturc.

vstcni n orator cricrrttor pronto source or cur- O variations in speedSystems oi motor control hat. which the motor is controlled in speedforce of the )plying snid LUOL,

these it 1 o ob all or 1L part of tncexcitation or the gcnczotor nornnsource, as thc clcctronimiro l'orcc ol 2:. nrely s cited gent or hn'vingat constant dirccti 1'1 is ordinarily not reve siblc. illlli.

proposed in which tilt W varying El genera? tor be tween i 1 iii-rainicistor.

system 'ihlo to have n. g

emtor supp ying such ijvtui', out it )0 obj' .iunurle to have or tordlllllltlli' 3G in which the spcod and direction of rotntiol l i iscontrolled by varying the \nlnc (Hui clcctrtnnoiirc iorcc oi n I no. is1 fully sell-excited. the the elcctronn force of this i 'dtnrlnnigrniisux.

My invention therefore broadly c controlling it gencrzttor whi Cormining the pol-n'ity oi its hold in cith desirod lily (-orr n. from v.

thcr exciting its Jicld hycurr Morn on it liy 11y inwi oi motor controlconsisting oi -10 armature oi Etiitl motor being practice. 'olt-cx'itcd, 2t

r llcr for .nrying the field elicitation of rent, and it (II sui gei torrand for connccting oi current to rcvcrsc the residue r and ztct-onrn;'ly pointod out in the dmr'ing t toying to be cut in and out by'usolenoid sWitchA, which in turn is responsive to the current strength of'iznury circuit of the motor as through a series in or Other means forvarying the speed of TrOlUl A may be used if desired. A generatorarmature i5 is driven by the motor A, being preferably directly thereto,and on the common shaft of the orator B is a. heavy fly wheel C. ierzt rll supplies current to the armature D or" motor. The motor D may be usedto drive 1, nntchinery. The licld windings d of the working motor aresupicd horn any di 1t current source through a switch 6. 1 held winding5) of the generator 13 are supplied i nn the same direct current sourceand the ratio-c ll oi' the main generator in series. The two 5; and dcontrolled by s niain controller H which is arranged to yin; theresistance in circuit rcspccti vcly with those two lield coils and toreverse lha; current in the coil b. The arm or handle h of this sept lonly be u. rind l0.

c controller is arranged so thatwhen its arrn h is moved on one side ofthe vertical the resistances '7 and ll) are ricd to control the speed ofthe motor D in one di rion, and W1 en moved on the other side or too yecol the I83! nnces 8 and 9 are varied to conrr the motor 11- in theother direction. The direction oi current through the coil 1) isreversed as the arm It passes through its Vertical position, at whichtime the olectronrotive force of the generator B last or near 1mm andsubstantially the full exciting current the coil is obtained lroni theseparate source of cct cut through the switch 6. Between the segmentsill and 12 01' the controller is arranged a resistance 13 to tsm up thefield discharge when the circuit The resistance 13 is aided rrhe coil 0is broken.

by :1 high resistance 14 permanently conoai across the coil b.

.A nominducivc resistance 15 is connected in series This resist cc tiohmic value several times as great as that of the field coil with whichit is in series. The purpose of this resistance is to diminish the timeconstant. of the field magnet b, for the time constant of a circuit is afunction of its inductance divided by its resistance. Therefore byincreasing the resistance t. the field circuit without increasing theinductance, the current strength being kept the same, the time constantof the circuit is reduced. By this means quick reversals of the motor Dmay be Inore readily obtained;

The operation of the system is as,iollows:'ihepri- Inary circuit ofmotor A. is closed and the motor started by moving the bar 2 to cut outthe starting resistance 1. The switch 4 is held open by its solenoid atthis time because of the heavy current required for starting the'motor.If desired, other means may be used to insure the open condition of thisswitch during starting. After the mo'tor has gained sufiicient speed andthe starting resistance has been cut out, the solenoid switch is allowedto close to cut outresistance 3 because of the decrease in the primarycurrent of motor A.

. with the motor A, and the fly-wheel stores mechanical ism of thcgenerator field.

energy by its rotation. During this starting the arm h is preferably inits vertical or of position. The switch (5 now being closed,.the motorfield (I is at its strongest, for it has none of the variable resistance9 or 10 in circuit with it. The generator field (a is deenergized. Thearm h is now gradually moved from the vertical toward the horizontal inthe proper direction to give the motor D the desired direction ofrotation. As this arm moves, say counter-clockwise,

it first connects thefield coil b in serieswith'thedirect current sourceand the armature B through the whole resistance 7, and then graduallycuts said resistance out of circuit. When the circuit of the fieldcoil 1) is completed the electromotive force of the generator armature Bis-negligible, and thus the direction of current from the direct currentsource determines the initial polarity of the generator iield. If thedesired direction of rotation of the motor D is the same as in its lastprevious operation, the current from the direct current source merelyreinforces the residual magnetlf the desired direction of rotation ofthe motor D is the reverse of that of its last previous operation, thecurrent from the direct current source reverses the residual magnetismof the generator field. In either case, as the generator B begins tobuildup its clectrolnotive force assists that of the direct currentsource to more strongly excite the generator field.

As the resistance 7 is cut out of circuit. the 'clcctromotive force ofthe armature I5 is int-roasiwl. lontinned movement of the arm It towardtho horizontal position also cuts tho resistance it) into thc circuit ofthe motor field coil ll. thus \vcakcning tihc motor ficld to assist inincreasing the spcod of the motor I). 'lhc speed which the motor I)acqnircs dcpcnds upon the extent of movcmcnt of tho arm it, full speedbeing obtainted when the full rcsisi'anco 7 has been cutout. and thefull resistant-c it) cut in. the clcctromotivc iorccs of the separatedirect currcni. source and the generator l} is prciorably such that.alter the generator i; has lit-gun to pick up, the groatcr part of theexcitation of the generator field is due in The fly-wheel'G andgenerator armature B are also started.

' as a gcncrator.

The rclation bciwccn,

the electromotive force of the generator armature, thus making thisgenerator practically fully self-excited.

If the load is heavy thc working motor D requires more power for itsstarting than the motor i\ can furnish. The current rising in thcprimaryof the transiormcr 5 by reason of this heavy load, the switch 4 isopened, thus inserting resistance 3 into the rotor circuit of motor A. vThis increases the slip of motor A and permits said motor to slow down,thus allowing the flywhecl'C to givc up some of the mechanical energyithas stored, which energy helps the motor A to drive the generator B tosupply electrical energy at the rate demanded by the motor D to drivethe load.

As the arm h is moved backward toward the vertical the field (I isstrengthened and the field I) weakened: The lattcr causes theelectromotivc force of the armature B to decrease. Both the increasingof its field strength and the decreasing of the electromotive forceimpressed upon its armature slow down the motor I),

armature 15, the latter now serving as a motor to help restore energy tothe fly-wheel There is a powerful braking effect upon the working motordue to its acting The diminished current in the primary of transformer 5also causes the solenoid switch 4 to close, thereby increasing the speedof motor A so that the latter may also supply energy to the fly-wheel(1. The fly-wheel thus stores up any excess of energy supplied when theratc of such supply exceeds the rate at which cncrgy is demanded by theworking motor, and gives up said storcd energy whenever the rate ofenergy dcinandcd is greater than the rate of energy supplied. When thearm h disconnects the auxiliary source of direct current from the fieldcoil .lJ-{thc resistance 13 is connected in circuit with said coil 1) totake the field discharge therefrom, the rcsistanccs l4 and i5 sting inthis. When the arinh is moved clockwise from the vertical the abovecycle is rcpcatcd, savc that. thc working motor D rotates in the otherdi rcction bccausc the direction of current in its armatnrc is rcvcrscd.

I have described my invention in what I now considcr to be its preferredform but many details in thc prccisc arrangements.shown and dc :ribcdmay be varied without departing from the spirit and scope of myinvention. All such obvious modifications I aim to covcr in the claims.

\\'hat I claim as new is:-- i. The method of reversing the electromutiveforce of a generator, which consists in reversing the residual magnetismof its field magnet: by current from ,htiptii'tili. source and thenenergizing saidiield magnet mainly by sclt'- -xcit:itio|1.

L. The incthod of varying the value and direction of tho olcctromotivoforce of .1 gcncrator which consists in energizing its ticld nmgnct'from its nrlnaturc' and from a scparatc source of current in stunts,varying the resistance in its field circuit, and reversing the current:snppiictl to the ticld magnet. from the sepuratc soul-cc oi curt-cut-\\'lnrn tho olcctromotivo force of the generator is less 4. The methodof reversing the electromotive force of an electric generator whichconsists in variably exciting the field magnet of the generator ironl'its armature, and reversing the residual magnetism of said field magnetwhen the self-excitation thereof is at a minimum.

5. The method or controlling an electric generator which consists indetermining the polarity of its field in either direction as desired bycurrent from a separate source, and in further exciting its field bycurrent from its own armature.

6. The method of controlling an electric motor which consists insupplying its armature trom a generator, selfexciting the field of saidgenerator, varying said excitation, and reversing the residual magnetismoi the field magnet of said generator when said self-excitation is at ornear a minimum.

7. The method of controlling an electric motor, which consists insupplying it from a generator, energizing the field of-the generatorjointly from its own armature and a separate source of current, varyingthe voltage of said generator, and reversing the current supplied to thegenerator field magnet from the separate source of current.

8. The method of reversing an electric motor, which consists insupplying it from a generator, self-exciting the field 0! saidgenerator, varying said excitatiomfand re versing the residual magnetismor the field magnet of. said generator by current from a separatesource.

9, The method of controlling the speed and direction of an electricfactor which consists in supplying the armatnre at said motor from thegenerator, energizing the field of the generator from its own armatureand a separate source of current in series, varying the resistance ofthe generator field circuit, and reversing the current supplied to thegenerator field magnet from the separate source of current when theelectromotive force of the generator is less than that or the separatesource. v

10. The method oi! controlling an electric motor which consists insupplying it from a generator, determining the polarity of the generatorfield by current from a separate source, further exciting said generatorby current from its own armature, and varying such further excitatlon,

11. in a system of electrical distribution, a generator, :1 main circuitsupplied thereby, a separate source of current, connections whereby thefield magnet of said generator is energized jointly from its armatureand from the scp a-' rate source and means for varying the fieldexcitation of said generator and for reversing the current-supplied tosaid field magnet from said separate source at a time when the generatorfield magnetization due to said separate source ls'greater than that dueto the generator. armature.

12. in combination, in self-excited generator, and means tor varying thefield excitation of said generator and for reversing the residualmagnetism of saidfieid magnet.

13. A system of electrical distribution, comprising a generator, a. maincircuit supplied thereby, a separate source of current, connectionswhereby the field.magnet of the generator is. supplied by the generatorarmature and said separate source or current in series, means forvarying the field excitation ofthe generator, and meansfor rev'ersingthe current supplied to said generator field magnet by said separatesource at the time the electromotive force of the main generator is lessthan that or the separate source.

14. In combination, a generator, a separate source of current, means forreversing the residual magnetism ot' the field of. said generator bycurrent from said separate source, and connections tor energizing thegenerator field mainly from the generator armature,

15. A system of motor control, comprising a motor, a seit-excitcdgenerator for supplying said motor, and means !or varying theself-excitation of said generator and for reversing the residualmagnetism of the field magnet 01 said generator when saidself-excitation is at or near a minimum.

16. A system of motor control, comprising a. motor, a generator forsupplying said motor, a separate source of ence of two witnesses.

current, connections for supplying the field windingsot said generatorjointly from the generator armature and from the separate source ofcurrent, and means for varying said field excitation and for reversingthe direction of the current snppliedto said field windings by saidseparate source. I

17. A. system of motor control, comprising a motor,'a generator forsupplying the armature of said motor, a separate source of current,connections whereby the field of said motor is supplied hy'said separatesource alone and the field or said generator by said separate source andthe generator armature in series, and means or varying the strength ofthe motor field and the strength and polarity of the generator field.

18. A system of motor control, comprising a motor, a

self-excited generator for supplying said motor, and means for varyingthe voltage of said generator and for reversing the residual magnetismof the field magnet of said generator.

19. A system of motor-control, comprising a motor, a sclfexcitedgenerator for supplying said motor, means for varying the voltage ofsaid generator' and for reversing the residual magnetism of the fieldmagnet of said generator, and a'resistance permanently connected acrossthe generator field coil. 7 I i i 20. A system of motor control,comprising a motor, a selflexcited generator for supplying saidmotor,means for varying the self-excitation of said generator and for re-.versing the residual magnetism of the generator field magnet, and aresistance permanently in series with the generator field coil.

21. A system of motor control, comprising a motor, a generator forsupplying said motor, a separate source of current, connections forsupplying the field windings of said generator jointly from thegenerator armature and the separate source of current, means for varyingsaid field excitation and for reversing the direction of current supplied to said field windings by said separate source, and a resistancearranged to be connectedjn the field circuit of the generator us saidseparate source is disconnected therefrom.

22. A-systcm of motor. control, comprising a source of current, a motorsupplied thereby, a generatordriven by said motor, a second motor thearmature otwhich is supplied by said generator, connections whereby thefield of said generator is supplied-jointly by. the generator armatureand another source of current, and means for varying the fieldexcitation of said generator and for reversing the current supplied tosaid generator fieldfmagnet by said other source.

23. A system of motor' control, comprising a source of current, a motorsupplied thereby, a self-excited generator driven by said motor, afly-wheel mechanically connected to said generator, a second motorsupplied by said generator, means for varying the field magnetization ofsaid generator and for reversing the residual magnetism of saidgenerator field, and means for causing the firstmotor to drop in speedwhen the load thereon exceeds a predetermined value. 4 5

34. .i system of motor control, comprising a source of current, a motorsupplied thereby, a generator driven by said motor, a flywheelmechanically connected to said motor, a second motor the armature ofwhich is supplied by said generator,,connections whereby the field orsaid generator is excited by the generator. armature and a separatesource of current jointly, means for reversing the residual magnetism ofsaid generator field magnet by reversing the current supplied thereto bysaid separate source, and means for causing said first motort'o increasein speed when the load thereon falls below a predetermined vaiue.

in testimony whereof I afllx my signature, in the pres- WILLIAM II.POWELL.

Witnesses (ino. B. Scum-1r, l nnn .i. Kmsnr.

